It is a conventional and well known practice to collect textile strand materials on a support tube, or bobbin, at various stages of a textile yarn manufacturing operation. In particular, in the collection of textile roving strands produced on a textile roving frame, such as on a Saco-Lowell Rovematic machine, the roving strands are continuously wound onto relatively large tubular bobbins, each of which is supportably received on and driven in rotation by a vertically disposed spindle to build the roving in a series of overlapping layers on the the surface of the bobbin.
Each drive spindle has a cylindrical main body and central vertically movable shaft, the upper end of which drivingly engages an upper end portion of the bobbin to rotate and vertically reciprocate the bobbin along the spindle main body past a horizontally fixed-position flyer which revolves about the bobbin to guide the roving onto the bobbin during its collection. A major portion of the interior wall of the bobbin through which the drive spindle extends is spaced from the adjacent guide surface of the spindle main body to permit radial contraction of the bobbin under force of tension exerted by the roving strand during winding and to facilitate removal of the bobbin from the spindle during doffing operations.
The lower end portion of the bobbin which reciprocates up and down along the guide surface of the spindle main body is of reduced internal diameter to closely surround and engage the adjacent outer surface of the spindle, thus providing stability of the bobbin during its rotation and proper guidance of the same on the spindle during the winding operation.
It is a current practice to manufacture tubular bobbins of the type described out of plastic in a molding operation. Typically the bobbin-forming molds comprise a pair of mating female mold parts which form a cavity to shape the exterior surfaces of the bobbin, and a male core, or force, of one piece construction which resides in the female cavity to form the shape of the interior surface of the bobbin. In such mold forming equipment employing a one piece force or core, it is necessary that the interior shape of the tubular bobbin formed in the mold be such as to permit withdrawal of the core from the bobbin after molding. For this reason, it has been the practice and deemed necessary to mold such plastic support bobbins in two separate pieces, a main tubular body having an internal passageway of uniform or slightly increasing internal diameter toward the open end of the bobbin from which the core must be removed, and a separate smaller diameter plastic ring which is thereafter inserted into and adhesively secured in the open end of the tubular main body, as by friction heat bonding, to provide the aforesaid reduced internal diameter portion at the base of the bobbin to closely surround the drive spindle and stabilize the bobbin during its rotation. Such a two piece construction not only adds to the cost of the manufacture of the bobbins, but the plastic ring inserts tend to accumulate lint at their surfaces of juncture with the main body of the bobbin. A build-up of lint on the interior surface of the bobbin often causes the bobbin to jam on the drive spindle during its vertical travel along the spindle main body, producing an unstable condition requiring shut-down of the roving frame to correct the situation. Such hang-up or drag of the bobbin on the drive spindle can also cause the bobbin to be thrown off the drive spindle with resultant danger to operators in the vicinity of the roving frame.